The invention relates to a mixture comprising diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids. Diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids are generally known as baking ingredients for baked products. More particularly, they are generally known for yeast-leavened products such as bread (especially white bread), tin bread, rolls, hard rolls, German crispy rolls, buns, rusks etc. These esters are able to improve the products in various respects as good leavening expressed as specific volume; even pores and acceptable crustiness. They are also known to improve the properties of dough such as its stability and rheology and are therefore often referred to as dough conditioners. The esters are further used in baking aids and in improved flour. The ED number of mixtures of diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids is E472e (DATEM).
The art has long described mixtures comprising diacetyl tartaric acid esters of mono-and diglycerides based on C12 to C22 fatty acids and their preparation. U.S. Pat. No. 2,236,516 (Frank J. Cahn et al) is an early patent specification disclosing products obtained by reacting diacetyl tartaric acid with glyceryl monostearate. U.S. Pat. No. 2,689,797 (Morris H. Joffe) discloses improvements in bread obtained by the incorporation of diacetyl tartaric esters of unsaturated and partially saturated mono and/or partial glycerides. U.S. Pat. No. 2,938,027 (Martell M. Gladstone) discloses the reaction between mixtures of acetylated anhydrides of food acids such as e.g. tartaric acid containing 4 to 95% of diacetylated tartaric acid and e.g. free acetic anhydride with partial glycerides of fatty acids to obtain improved products. U.S. Pat. No. 3,443,969 (Nobuo Nakejima et al) discloses diacetyltartaric esters of purified (molecular distilled) monoglycerides of vegetable oils. GB-A-1,220,488 (Aktieselskabet Grindstedvaerket) discloses the preparation of an emulsifier obtained by reacting, e.g., distilled glycerol monostearate with diacetyl tartaric anhydride in certain molar ratios followed by prolonged heating to 135-190xc2x0 C. as to obtain by polymerization a satisfactory oil-in-water emulsifier of higher molecular weight, which apparently contains polymeric esters due to splitting off acetic acid and water. GB-A-1,344,518 (Dynamit Nobel A.G.) discloses solid acetyltartaric esters obtained by reacting at least partially acetylated tartaric acid with partial glycerides containing 55-65% monoglyceride and an iodine value below 5 which contain per mole of partial glyceride 0.91-1.8 mole tartaric acid residues and 1.8-3.4 mole acetic acid residues. These esters are free flowing powders whereas the traditional esters have a waxy or honey-like consistency. This difference in physical properties is due to the fact that these powders contain appreciable quantities of say about 0.3 mol % of glyceride esters of monoacetyl tartaric residues and/or even non-acetylated tartaric acid residues. Conventional acetylated tartaric acid esters of mono- and/or diglycerides are mono- and/or diglyceride esters of (almost) pure diacetylated tartaric acid (anhydride). The products according to the present invention are also very low in esters of monoacetylated tartaric acid (anhydride).
Although the current diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids are valuable products they are often somewhat defective as to:
1 specific volume of the baked product obtained;
2. stability as to leavening under the influence of yeast; and/or
3. stability properties of the dough prepared.
It is an object of the present invention to provide a mixture comprising diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids yielding a performance which is improved in at least one of the properties mentioned above. Moreover, the present invention also provides a process for the preparation of the aforementioned mixture(s) of the diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids by reaction of diacetylated tartaric acid anhydride and mono- and diglycerides C12 to C22 fatty acids at a relatively low temperature combined with a short reaction time, which is more economical than most of the current processes.
The FIGURE is a plot from a NMR.
The invention therefore provides in a first embodiment a mixture comprising diacetyl tartaric acid esters on mono- and diglycerides based on C12 to C22 fatty acids. The mixture comprises diacetyl tartaric acid glycerol monoesters containing: (A) one fatty acid group, one diacetylated tartaric acid monoester group and a free hydroxyl group and (B) one fatty acid group and two diacetylated tartaric acid monoester groups, wherein
1. the concentration of (A) above in the total mixture, obtained by dividing the molar amount of (A) by the sum of the molar amounts of all components in the mixture and multiplying by 100, is at least 45%, preferably at least 50%, and
2. the fraction obtained by dividing the molar amount of (A) above by the combined molar amounts of (A) and (B) taken together is at least 0.70, preferably at least 0.72 and in which the molar amounts are determined by the NMR method herein described.
These NMR measurements were performed at 50xc2x0 C. in CDCl3 on a Jeol JNMR EX400 FT-NMR spectrometer operating at 400 MHz for 1H. Typically, 20 mg of sample was dissolved in 0.5 ml of solvent. To prevent overlap of the H2O resonance with resonances of the product, the pH of the sample was lowered to approximately 4 by adding acetic acid. The pulse delay (PD) time had to be chosen such that full relaxation of the signals takes place (PD greater than 5T1).
The contents of (A) and (B) (mol %) can be calculated from the integral values:
P:xcex4=4.0 ppm to 4.5 ppm
Q:xcex4=4.7 ppm to 4.9 ppm
R:xcex4=5.0 ppm to 5.2 ppm
S:xcex4=5.2 ppm to 5.4 ppm,
e.g from the graph as illustrated in FIG. 1 by the formulae:                               (          A          )                =                              [                                                            P                  -                                      (                                                                  4                        ⁢                        Q                                            +                                              2                        ⁢                        R                                            +                                              4                        ⁢                        S                                                              )                                                  5                                                              P                  xe2x80x2                                +                Q                +                R                +                S                                      ]                    ·                      100            ⁡                          [                              mol                ⁢                                  xe2x80x83                                ⁢                %                            ]                                                                        (          B          )                =                              [                          S                                                P                  xe2x80x2                                +                Q                +                R                +                S                                      ]                    ·                      100            ⁡                          [                              mol                ⁢                                  xe2x80x83                                ⁢                %                            ]                                                                        P          xe2x80x2                =                              P            -                          (                                                4                  ⁢                  Q                                +                                  2                  ⁢                  R                                +                                  4                  ⁢                  S                                            )                                5                    
N.B. All these integral values have to be corrected for glycerol mono-, di- and triesters of C14 to C18 fatty acids, if any, first.
Or, in words, in the formulae:
(A) equals a fraction of which the numerator is 100 times (P minus the sum of 4 times Q plus twice R plus 4 times S) divided by 5 and the denominator is (the sum of Pxe2x80x2 plus Q plus R plus S in which Pxe2x80x2 is P minus the sum of 4 times Q plus twice R plus four times S) divided by 5; and
(B) equals a fraction of which the numerator is S multiplied by 100 and the denominator is (the sum of Pxe2x80x2 plus Q plus R plus S in which Pxe2x80x2 is P minus the sum of 4 times Q plus twice R plus four times S) divided by 5.
In case a product is at stake which contains fatty acid triglyceride as an extender as may be the case the NMR data measured need to be corrected for this percentage of triglyceride. Therefore the amount of triglyceride, if present, has to be determined and the method disclosed by P. Quinlan and H. J. Weiser Jr in JAOCS 35, 325-6 (1958) was found suitable. We used a modified method employing toluene (technical grade) instead of benzene and silicagel 60, no 1.07734.110 cx Merck, 20-230 mesh which activated with 9 wt % of water instead of 5% of water. The NMR signals of the specific fatty acid triglycerides which are needed are known from Sadtler Index of 1 H-NMR spectra (Sadtler Research Laboratories (Biorad) Philadelphia, Pa., USA).
In case a product is at stake in which mono- and/or diglycerides are used as an extender, the analysis of the percentage diglycerides was carried out by proton NMR applying the same method as used for the determination of A and B above. 1-2 diglycerides were measured at xcex4=4.30 ppm, and 1-3 diglycerides were measured at xcex4=4.05 to 4.25 ppm. Both components were calculated with formula:       Mol    ⁢          xe2x80x83        ⁢    %    ⁢          xe2x80x83        ⁢    Diglycerides    =            I      4.30                      P        xe2x80x2            +      Q      +      R      +      S      
Since 1-3 diglycerides interfere with A, a mathematical correction had to be applied. The basis for this correction is the known fixed ratio between 1-2 and 1-3 diglycerides of 40:60 wt %. From literature (JAOCS 37; August 1960 and JAOCS 23, 390 (1960)) a general ratio from 35:65 to 49:51 depending on the chain length (C12-C18) and temperature (20-200xc2x0 C.) of the fatty acids is known. Since in most commercial emulsifiers the majority of fatty acids used are of C16 and C18 chain length, a 1-2, 1-3 diglycerides ratio of 2:3 was been applied. In case diglycerides were present as indicated at xcex4=4.30 ppm, the integral P has to be corrected by subtracting two and a half times the integral value of 1-2 diglycerides at xcex4=4.30 ppm.
The integral value for triglycerides has been calculated according to:       I    Tri    =                    G        ·                  I          A                ·                  M          A                    +              G        ·                  I          B                                              (                      1            -            G                    )                ·                  M          Tri                    +              G        ·                  M          B                    
wherein G is the weight fraction triglycerides determined using the modified method of Quinlan and Weiser in JAOCS 1958 cited above, MA, MB and MTri the average molecular masses of components A, B and triglycerides respectively and IA and IB the integral values obtained by NMR for components A and B including triglycerides.
Mono-diglycerides of C12-C22 fatty acids which can be used in the preparation of the mixtures of diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids according to the present invention are obtainable from triglycerides of these fatty acids which can be of both vegetable and animal origin, e.g., from soya bean oil, coconut oil, babussa oil, palm oil, sunflower oil, lard, tallow and fish oil, optionally hydrogenated or fractionated. Mixtures of mainly palmitic and stearic acid are preferred. The mono-diglycerides can be prepared by interesterification with glycerol, usually in the presence of an alkaline catalyst. Mostly the triglyceride oil and the glycerol reacted are free from water or moisture. Further details of this reaction are disclosed in, for example, U.S. Pat. No. 2,875,221 (Bimbaum). Esterification leads to mixtures of mono- and diglycerides. After removal of water and unreacted glycerol the product obtained contained up to 65 wt % of monoglycerides. More pure monoglycerides can be obtained by molecular distilling the monoglycerides from the mixture and results in monoglycerides containing at least 90% monoglycerides. Such distilled products are e.g. marketed under the tradename Hymono ex Quest, Naarden, Netherlands. Crystallization and other fractionation processes might also yield similar relatively pure products. The term distilled monoglycerides therefore here has a wider interpretation than the literal sense and covers also purified monoglycerides obtained by other means than distillation. Monoglycerides containing 60 to 80% monoglycerides are usually prepared by diluting distilled monoglycerides with undistilled mono-diglycerides. They are marketed as such and in admixture with triglyceride fat. Monoglycerides containing from 60, preferably 70, to 99, more preferably 80 to 99 wt % of monoglyceride can be used for preparing the present mixtures. In the practice of the present invention it is preferred to use distilled products especially those obtained by molecular or short path distillation.
Diacetylated tartaric acid anhydride and derivatives are usually prepared from tartaric acid (dextro, levo, racemic or meso), preferably from natural=Lxe2x88x92(+) tartaric acid or racemic tartaric acid and excess acetic anhydride by heating in the presence of suitable catalyst like sulphuric acid and distilling of acetic acid. The diacetylated tartaric acid (anhydride) used in the practice of the present invention is substantially diacetylated material and contains less than 2.5 mol %, preferably less than 1 mol %, more preferably less than 0.5 mol % of monoacetylated material. Further details are disclosed, for example, in U.S. Pat. No. 2,520,139 (Fuchs) and WO 96/35658 (Quest International) especially for D- and DL-tartaric acid as starting materials. It is normal practice to use food grade or P.A. grade materials in the preparation. In another embodiment of the invention the novel mixture of diacetylated tartaric acid esters of mono- and/or diglycerides described above is diluted with a suitable edible and/or food grade extender (e.g. fatty acid triglyceride or mono- and/or diglyceride of fatty acid(s) or another emulsifying agent) to any cost-effective level at which improved baking properties are still noticeable. Usually the amount of extender ranges between 10 and 50, preferably 20 and 40 wt % in the diluted product.
In a preferred embodiment the invention provides a mixture, in which the concentration of (A) above in the mixture, obtained by dividing the molar amount of (A) by the sum of the molar amounts of all components in the mixture and multiplying by 100 is at least 55%, preferably at least 60% (or e.g at least 65%).
In another preferred embodiment the invention provides a mixture as specified above in which the fraction obtained by dividing the molar amount of (A) above by the combined molar amounts of (A) and (B) taken together is at least 0.75, preferably at least 0.85 (or, e.g., at least 0.90).
In another preferred embodiment the invention provides a mixture as specified above in which the reaction mixture is based on distilled monoglycerides and contains less than 5, preferably less than 4 wt % of diacetyl tartaric esters of fatty acid diglycerides.
In another preferred embodiment the invention provides a mixture as specified above in which the mixture is based on mono- and diglycerides of substantially fully saturated C16 and/or C18 fatty acids.
In another embodiment the invention provides a process for preparing a novel mixture comprising diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids as described above in which diacetylated tartaric acid anhydride is molten and reacted at 135-175xc2x0 C. with molten C12 to C22 fatty acid partial glycerides comprising 60-99, preferably 70 to 99 wt %, of monoglycerides, preferably in an inert atmosphere, for a reaction period of from 0.5 to 30, preferably from 1 to 15 minutes, more preferably from 2 to 10 minutes in the presence of an effective amount of a catalyst. Suitable catalysts are, e.g., alkaline compounds like sodium, potassium, magnesium or calcium carboxylates such as their stearates, palmitates and other carboxylic acid salts, e.g., in amounts from 0.05 to 0.5 wt percent calculated on the reaction mixture.
In another embodiment the invention provides a process for preparing a process for preparing a novel mixture comprising diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids, more preferably based on saturated C16 to C18 fatty acids as described above, in which the mono-diglycerides containing 60 to 99, preferably 70 to 99 wt. % of monoglycerides are molten and solid diacetylated tartaric acid anhydride is dissolved therein and reacted in the liquid phase, preferably in an inert atmosphere, with the mono-diglycerides at a temperature between 60xc2x0 C. and 120xc2x0 C. for a period of 5 to 30 minutes in the presence of an effective amount of an alkaline catalyst. This reaction usually takes place frilly in the liquid phase.
The preparation of mixtures of diacetyl tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids according to the present invention can be carried out batchwise (e.g. in a stirred tank reactor), semi-continuously (e.g. in two or more stirred tank reactors operating in turn in the sequence filling, reacting and discharging) or continuously (e.g. in a (multi)-tube reactor or in a cascade of stirred tank reactors). Another possibility is to carry out the reaction in a microwave [stirred tube(s) or tube] reactor. The reaction itself is exothermic so that the (reaction) temperature may rise so rapidly that the product deteriorates whereas at too low a reaction temperature diacetyl tartaric acid anhydride may solidify. Consequently the equipment, especially for continuous processing, needs to be equipped with suitable means for a tight temperature control comprising an advanced cooling system. Therefore equipment suggested for the continuous preparation of monoglycerides is unsuitable for the preparation of the mixture of diacetyl esters of mono- and/or diglycerides according to the present invention.
In another embodiment the invention provides a process as specified above in which the reaction between diacetylated tartaric acid anhydride and mono- and diglycerides based on C12 to C22 fatty acids is carried out in a continuous manner in a suitable reactor e.g. as outlined above.
The products obtainable by the processes specified above can be finished by spray-cooling, cryogenic milling under an inert gas like liquid nitrogen, extrusion and/or taking up in a suitable extender like triglyceride or monoglycerides (known useful bakery improvers), also an anti-caking agent may be added such as e.g. calcium orthophosphate and calcium carbonate. They can be marketed directly as emulsifier, as dough conditioner, in flour and in bakery improvers (baking ingredients) for yeast-leavened baked products.
The invention also provides the use of a mixture comprising diacetylated tartaric acid esters of mono- and diglycerides based on C12 to C22 fatty acids as specified above as emulsifier, dough conditioner, in improved flour (mixes) and in bakery improvers/baking ingredients for yeast-leavened baked products.
The invention also provides baked products in which a mixture comprising diacetyl tartaric acid esters on mono- and diglycerides based of C12 to C22, preferably C16 to C18, fatty acids as specified above has been incorporated. This includes baking ingredients for baked products and more particularly for yeast-leavened products such as bread (especially white bread), tin bread, rolls, hard rolls, German crispy rolls, buns, rusks etc.
All percentages and parts mentioned herein are on a molar basis unless otherwise indicated.
The invention is illustrated by the following non-limiting examples.